1. Industrial Use Field
This invention relates to a flywheel assembly which can absorb vibration of an entered power.
2. Prior Art and its Problem
In FIG. 3 which is a schematic structural view of a conventional clutch disc, 10 is a power entered side from an engine, and 12 is an output side from which the power is transmitted to a speed changer etc., for example. A first-stage torsion spring 14a, a second stage torsion spring 14b and a third-stage torsion spring 14c are interposed between the input side 10 and the output side 12, and specified torsional angular clearances 14d and 14e are provided for the second-stage torsion spring 14b and the third-stage torsion spring 14c. Further, a first-stage hysteresis torque generating mechanism 16a, a second-stage hysteresis torque generating mechanism 16b and a third-stage hysteresis torque generating mechanism 16c are interposed in the same manner as above, and clearances 16d and 16e are provided for the second-stage hysteresis torque generating mechanism 16b and the third-stage hysteresis torque generating mechanism 16c.
In the above conventional embodiment, with an increase in a torsion angle as illustrated in FIG. 4 showing a transmitting torque T in relation to a torsion angle R, torsion characteristics change from a first-stage torsion characteristic kd1 and a first-stage hysteresis characteristic Th1 generated by the first-stage torsion spring 14a and the first-stage hysteresis torque generating mechanism 16a, to a third-stage torsion characteristic kd3 and a third-stage hysteresis characteristic Th3 generated by the third-stage torsion spring 14c and the third-stage hysteresis torque generating mechanism 16c. However, these characteristics include the following defects.
It is preferable to minimize the first-stage torsion characteristic kd1--the third-stage torsion characteristic kd3 as a countermeasure against tooth chattering sound emitted from a speed changer under its neutral state and tooth chattering sound generated from the speed changer and a differential mechanism during running. On the other hand, it is required to set the first-stage torsion characteristic kd1--the third-stage torsion characteristic kd3 to large values as a countermeasure against low frequency vibrations.
Accordingly, it becomes necessary to set the torque characteristic of FIG. 4 depending on a respective characteristic required by every vehicle. Moreover, in recent years a demand level for clutch to control abnormal sound and vibration becomes higher and higher, so that in some occasions it is required to simultaneously provide a characteristic, which can not be attained by a conventional construction, such that the conflicting countermeasures against abnormal sound and low frequency vibration must be taken at the same time as mentioned above.
Therefore, a technique for positively absorbing vibrations from engine in a flywheel has been developed.
There are prior arts, in which an auxiliary flywheel 26a and a damper 26b are connected in series in between a conventional clutch disc 20, a flywheel 22 and a crank shaft 24 as shown in FIG. 5, and an auxiliary flywheel 26a is installed through a torsion spring 26c in parallel with the flywheel 22 as shown in FIG. 6.
However, since the above-mentioned prior arts have insufficient vibration absorbing abilities, it is desired to develope a flywheel assembly having a further efficient vibration absorbing ability.